Production of macrophage migration inhibitory factor by human and murine neuroblastoma.

Tumor cells avoid immune recognition by subverting the ability of the immune system to mount an inflammatory response that generates cytotoxic effector cells. This can be achieved through cytokine production by the tumor itself. Our objective was to determine the cytokine profile of neuroblastoma (NB) lesions in tumor vaccine models. We found that the murine NB cell line, Neuro2a, secretes macrophage migration inhibitory factor, MIF, a multifunctional cytokine with the potential to block effective immune responses to a tumor. Patient-derived NB cell lines were also found to produce MIF. MIF production by NB was documented at the level of RNA by RNAse protection, soluble cytokine production by ELISA, and in a macrophage migration assay. Our studies also confirmed reports of IL-6 production by human NB cell lines. NB culture-derived MIF was also shown to activate tumor cell migration. This supports the hypothesis that MIF is a tumor-derived cytokine that may play a role in NB aggressiveness and evasion of immune recognition.